Further consideration on Multi-STA Block ACK Month Year doc.: IEEE 802.11-yy/xxxxr0 May 2015 Further consideration on Multi-STA Block ACK Date: 2015-05-11 Authors: Name Affiliation Address Phone Email Jeongki Kim LG Electronics 19, Yangjae-daero 11gil, Seocho-gu, Seoul 137-130, Korea   jeongki.kim@lge.com Wookbong Lee wookbong.lee@lge.com Jinyoung Chun jiny.chun@lge.com Jinsoo Choi js.choi@lge.com Kiseon Ryu kiseon.ryu@lge.com Suhwook Kim suhwook.kim@lge.com Hyeyoung Choi hy0117.choi@lge.com Dongguk Lim dongguk.lim@lge.com Eunsung Park esung.park@lge.com Jinmin Kim jinmin1230.kim@lge.com HanGyu Cho hg.cho@lge.com Jeongki Kim, LG Electronics John Doe, Some Company

Authors (continued) May 2015 Albert Van Zelst Alfred Asterjadhi Name Affiliation Address Phone Email Albert Van Zelst Qualcomm Straatweg 66-S Breukelen, 3621 BR Netherlands   allert@qti.qualcomm.com Alfred Asterjadhi 5775 Morehouse Dr. San Diego, CA, USA aasterja@qti.qualcomm.com Bin Tian btian@qti.qualcomm.com Carlos Aldana 1700 Technology Drive San Jose, CA 95110, USA caldana@qca.qualcomm.com George Cherian gcherian@qti.qualcomm.com Gwendolyn Barriac gbarriac@qti.qualcomm.com Hemanth Sampath hsampath@qti.qualcomm.com Menzo Wentink mwentink@qti.qualcomm.com Richard Van Nee rvannee@qti.qualcomm.com Rolf De Vegt rolfv@qca.qualcomm.com Sameer Vermani svverman@qti.qualcomm.com Simone Merlin smerlin@qti.qualcomm.com Tevfik Yucek   tyucek@qca.qualcomm.com VK Jones vkjones@qca.qualcomm.com Youhan Kim youhank@qca.qualcomm.com Jeongki Kim, LG Electronics

2111 NE 25th Ave, Hillsboro OR 97124, USA May 2015 Authors (continued) Name Affiliation Address Phone Email Ron Porat Broadcom   rporat@broadcom.com Matthew Fischer mfischer@broadcom.com Sriram Venkateswaran Tu Nguyen Vinko Erceg Robert Stacey Intel 2111 NE 25th Ave, Hillsboro OR 97124, USA   +1-503-724-893   robert.stacey@intel.com Eldad Perahia eldad.perahia@intel.com Shahrnaz Azizi shahrnaz.azizi@intel.com Po-Kai Huang po-kai.huang@intel.com Qinghua Li quinghua.li@intel.com Laurent Cariou laurent.cariou@intel.com Xiaogang Chen xiaogang.c.chen@intel.com Chitto Ghosh chittabrata.ghosh@intel.com Rongzhen Yang rongzhen.yang@intel.com Jeongki Kim, LG Electronics

Authors (continued) May 2015 Phillip Barber Peter Loc Le Liu Jun Luo Name Affiliation Address Phone Email Phillip Barber Huawei The Lone Star State, TX   pbarber@broadbandmobiletech.com Peter Loc peterloc@iwirelesstech.com Le Liu F1-17, Huawei Base, Bantian, Shenzhen +86-18601656691 liule@huawei.com Jun Luo 5B-N8, No.2222 Xinjinqiao Road, Pudong, Shanghai jun.l@huawei.com Yi Luo +86-18665891036 Roy.luoyi@huawei.com Yingpei Lin linyingpei@huawei.com Jiyong Pang pangjiyong@huawei.com Zhigang Rong 10180 Telesis Court, Suite 365, San Diego, CA  92121 NA zhigang.rong@huawei.com Rob Sun 303 Terry Fox, Suite 400 Kanata, Ottawa, Canada Rob.Sun@huawei.com David X. Yang david.yangxun@huawei.com Yunsong Yang yangyunsong@huawei.com Zhou Lan F1-17, Huawei Base, Bantian, SHenzhen +86-18565826350 Lanzhou1@huawei.com Junghoon Suh Junghoon.Suh@huawei.com Jiayin Zhang zhangjiayin@huawei.com Jeongki Kim, LG Electronics

Authors (continued) May 2015 Hongyuan Zhang Marvell Name Affiliation Address Phone Email Hongyuan Zhang Marvell 5488 Marvell Lane, Santa Clara, CA, 95054 408-222-2500 hongyuan@marvell.com Yakun Sun yakunsun@marvell.com Lei Wang Leileiw@marvell.com Liwen Chu liwenchu@marvell.com Mingguan Xu mxu@marvell.com Jinjing Jiang jinjing@marvell.com Yan Zhang yzhang@marvell.com Rui Cao ruicao@marvell.com Jie Huang jiehuang@marvell.com Sudhir Srinivasa sudhirs@marvell.com Saga Tamhane sagar@marvell.com Mao Yu my@marvel..com Edward Au edwardau@marvell.com Hui-Ling Lou hlou@marvell.com Thomas Derham Orange thomas.derham@orange.com Jeongki Kim, LG Electronics

Authors (continued) May 2015 Fei Tong Hyunjeong Kang Samsung Name Affiliation Address Phone Email Fei Tong Samsung Innovation Park, Cambridge CB4 0DS (U.K.) +44 1223 434633 f.tong@samsung.com Hyunjeong Kang Maetan 3-dong; Yongtong-Gu Suwon; South Korea +82-31-279-9028 hyunjeong.kang@samsung.com Kaushik Josiam 1301, E. Lookout Dr, Richardson TX 75070 (972) 761 7437 k.josiam@samsung.com Mark Rison +44 1223 434600 m.rison@samsung.com Rakesh Taori (972) 761 7470 rakesh.taori@samsung.com Sanghyun Chang +82-10-8864-1751 s29.chang@samsung.com Yasushi Takatori NTT 1-1 Hikari-no-oka, Yokosuka, Kanagawa 239-0847 Japan   takatori.yasushi@lab.ntt.co.jp Yasuhiko Inoue inoue.yasuhiko@lab.ntt.co.jp Yusuke Asai asai.yusuke@lab.ntt.co.jp Koichi Ishihara ishihara.koichi@lab.ntt.co.jp Akira Kishida kishida.akira@lab.ntt.co.jp Akira Yamada NTT DOCOMO 3-6, Hikarinooka, Yokosuka-shi, Kanagawa, 239-8536, Japan yamadaakira@nttdocomo.com Fujio Watanabe 3240 Hillview Ave, Palo Alto, CA 94304 watanabe@docomoinnovations.com Haralabos Papadopoulos hpapadopoulos@docomoinnovations.com Jeongki Kim, LG Electronics

Authors (continued) May 2015 James Yee Mediatek Name Affiliation Address Phone Email James Yee Mediatek No. 1 Dusing 1st Road, Hsinchu, Taiwan +886-3-567-0766  james.yee@mediatek.com Alan Jauh   alan.jauh@mediatek.com Chingwa Hu chinghwa.yu@mediatek.com Frank Hsu frank.hsu@mediatek.com Thomas Pare USA 2860 Junction Ave, San Jose, CA 95134, USA +1-408-526-1899 thomas.pare@mediatek.com ChaoChun Wang chaochun.wang@mediatek.com James Wang james.wang@mediatek.com Jianhan Liu Jianhan.Liu@mediatek.com Tianyu Wu tianyu.wu@mediatek.com Russell Huang russell.huang@mediatek.com Bo Sun ZTE #9 Wuxingduan, Xifeng Rd., Xi'an, China   sun.bo1@zte.com.cn Kaiying Lv lv.kaiying@zte.com.cn Yonggang Fang yfang@ztetx.com Ke Yao yao.ke5@zte.com.cn Weimin Xing xing.weimin@zte.com.cn Brian Hart Cisco Systems 170 W Tasman Dr, San Jose, CA 95134 brianh@cisco.com Pooya Monajemi pmonajem@cisco.com Jeongki Kim, LG Electronics

Authors (continued) May 2015 Apple Jeongki Kim, LG Electronics Name Affiliation Address Phone Email Joonsuk Kim Apple joonsuk@apple.com Aon Mujtaba     mujtaba@apple.com Guoqing Li guoqing_li@apple.com Eric Wong ericwong@apple.com Chris Hartman  chartman@apple.com Jeongki Kim, LG Electronics

May 2015 Introduction In legacy system[3], ACK is sent for single MPDU and BA is sent for A-MPDU with multiple MPDUs Multi-STA Block Ack (M-BA) frame can be used for acknowledge for UL MU frames [1][2] Add an indication that the frame is a multi-STA BA (TBD) …… If B11 in the per-TID info field is set, then the BlockAck bitmap and the SC subfields in the BA Info field are not present and this BA Info field indicates an ACK for the STA with AID indicated in the per-TID info field B0-B10= AID B11= ACK/BA B0-B10= AID B11= ACK/BA Jeongki Kim, LG Electronics

May 2015 Motivation The current M-BA frame is used to convey the Block ACKs of multiple STAs in response to UL MU frames M-BA overhead will be increased according to increasing the number of STAs which sent UL MU frames Duration of M-BA frame will exceed the EIFS duration very often and long M-BA frame will degrade the UL MU performance This contribution propose an approach to reduce the M-BA frame overhead # of STAs 2 4 8 16 M-BA duration (us) 88 120 184 312 Assumptions: 11a PPDU format(20us preamble), MCS0, Service field (2bytes), Tail (6bits) Jeongki Kim, LG Electronics

May 2015 Proposal AP can correctly receive all MPDUs in an A-MPDU sent by a STA among UL MU PPDUs In this case (i.e., STA2), B11 bit in the Per TID Info field is set to 1 to indicate that SSC and bitmap are not present. If a STA that sent an A-MPDU receives an M-BA with B11 set to 1 in the BA Information pertaining to it, the STA operates as if it had received an immediate BA acknowledging all the MPDUs sent in the A-MPDU Such an M-BA can be used if there are any other unacknowledged MPDUs from an earlier A-MPDU, but does not acknowledge those. Trigger frame M-BA (STA1: B11=0, AID, SSC, bitmap) (STA2: B11=1, AID) AP MPDU (SN =3) Ack_Policy=00 MPDU (SN =4) MPDU (SN =4) MPDU (SN =5) STA1 MPDU (SN =7) Ack_Policy=00 MPDU (SN =8) MPDU (SN =9) STA2 UL MU frames Jeongki Kim, LG Electronics

Overhead comparison May 2015 How much gain? Assumptions: 11a PPDU format(20us preamble), MCS0, Service field (2bytes), Tail (6bits) The number of STAs with ACK A-MPDU depends on the channel environment Total # of STAs (8) Total # of STAs (16) Overhead reduction gain: 58.7% (108us) for 8 ACK STAs among 8 STAs Overhead reduction gain: 69.2% (216us) for 16 ACK STAs among 16 STAs Number of STAs with ACK among 8 STAs Number of STAs with ACK among 16 STAs Jeongki Kim, LG Electronics

May 2015 Discussions UL MU TXs are initiated by trigger frame (AP) and will be protected by trigger frame i.e., A-MPDU TXs with partial error (i.e., BA) will hardly happen in UL MU and the probability for ACK A-MPDUs will be much more than that at numerical analysis, especially in RTS/CTS exchange for UL MU In case of multiple UL MU frames in a TXOP, multiple M-BA frames are sent and we can save more M-BA duration E.g.,) If 108/216us (8/16 STAs, MCS0) per a M-BA is saved, we can save up to 648/1296 us totally for 6 M-BA frames The saved time duration by reduced M-BA frame will be used for triggering other UL frame (e.g., buffer status request (BSR) , additional UL data, etc.) or for DL frame transmission (e.g., data, management, etc.) Jeongki Kim, LG Electronics

May 2015 Conclusion M-BA frame size needs to be minimized because the long M-BA will decrease the UL MU performance and the long M-BA duration can exceed the EIFS duration often In UL MU procedure, the number of A-MPDUs with all ACK MPDUs will be much more than that of A-MPDU with partial ACK MPDUs because most of A-MPDUs sent by STAs can be protected by trigger frame We propose to use B11 bit in per-TID Info field in order to indicate the ACK of an A-MPDU sent by a STA during UL MU procedure (i.e., M-BA overhead reduction) Jeongki Kim, LG Electronics

References [1] 11-15-0132-04-00ax-spec-framework May 2015 References [1] 11-15-0132-04-00ax-spec-framework [2] 11-15-0366-02-00ax-multi-sta-ba [3] P802.11 REVmc_D4.0 Jeongki Kim, LG Electronics

May 2015 Straw Poll Do you agree to modify the sub-clause 7.2 in 11ax SFD as follows? 7.2 Multi-STA BA ….. If B11 in the per-TID info field is set, then the BlockAck bitmap and the SC subfields in the BA Info field are not present and this BA Info field indicates an ACK for of either single MPDU or all MPDUs carried in the eliciting PPDU that was transmitted by the STA whose the STA with AID is indicated in the per-TID info field Jeongki Kim, LG Electronics